1. Field of the Invention
The invention relates to a digital signal reproducing apparatus and, more particularly, to a digital signal reproducing apparatus, such as a rotary-head digital audio tape recorder (R-DAT).
2. Description of the Background
In a previously proposed digital signal reproducing apparatus, for example, a rotary-head digital audio tape recorder (R-DAT), a pair of tracks formed by a pair of magnetic heads are called an interleave pair, and a kind of interleaving is performed in which two tracks constitute one frame. Frame addresses recorded on the tracks of the interleave pair have identical values, so that the interleave pair can be easily identified from their frame addresses upon playback.
It is to be noted that in the typical R-DAT apparatus a memory functioning as a buffer is provided for time-base expansion and also for performing the deinterleave operation.
Because a frame-completion type interleave is applied in the R-DAT apparatus as mentioned above, in which two tracks complete one frame, unless data having the same frame address is read into the same block of the memory, an interleave error occurs causing the error correction circuit to perform erroneous correction resulting in the reproduced sound not being smooth and continuous. To overcome these drawbacks the following techniques have been proposed:
As described in U.S. patent application Ser. No. 21,226 filed Mar. 3, 1987 proposed by the present applicant and now U.S. Pat. No. 4,799,221, all the reproduced data is read into a memory, and if it is detected that the data does not have the same frame address during the reproduction processing, erasure correction in an error correction circuit is prohibited or an interpolation operation is enforced.
As described in U.S. patent application Ser. No. 87,093 filed Aug. 19, 1987 proposed by the present applicant and now U.S. Pat. No. 4,875,111, when the reproduced data is read into the memory, a frame address derived from the reproduced signal is used as a write address for the memory so that no interleave error occurs in the memory.
Nevertheless, the following problems exist in the above-mentioned techniques, respectively. When it is detected that the data does not have the same frame address, the correction capability of the error correction circuit must be lowered or a forced interpolation must be done. In the case of the forced interpolation, this results in interpolation being carried out even when the data is correct. This is inefficient. When using a reproduced frame address as the write address for the memory, a large-capacity memory is needed, and this is disadvantageous in terms of hardware size and cost.